Crank press



K, GTZ

CRANK PRESS Dec. 3, 1935.

Filed Oct. 19, 1935 3 Sheets-Sheet 1 Dec. 3, 1935. K/GTZ 2,023,319

CRANK PRESS Filed Oct. 19, 1955 3 Sheets-Sheet 2 Inventor:

Dec. 3, 1935. K, GTz 2,023,319

CRANK PRES S Filed'OCb; 19, 1953 3 SheetSSheet 5 /n vento/z' PatentedDec. 3, 1935 UNITED STATES PATENT OFFICE Application October 19, 1933,Serial No. 694,319 In Germany Gctober 19, 1932 13 Claims.

This invention relates to a press in which the l crank actuating thepress plunger, which shall be referred to as the pressing crank, is notdirectly connected to the driving machine or to the handle for operationby hand, but an auxiliary crank is interposed in this connection, whichon the one hand is turned by the driving machine or the handle, buttransmits its motion to the pressing crank only through one or more pullbars, links or the like. ln place of the pressing crank or the auxiliarycrank or both eccentrics may be employed.

A crank press with two cranks is thus obtained and the motion of thepress plunger can in this way be iniiuenced in a variety of ways inspite of the approximately constant motion of the driving machine.

It is the object of this invention to arrange the two cranks so withrespect to one another that the velocity of the motion of the pressplunger will steadily decrease from the upper dead centre position tothe bottom dead centre position and to provide other means which renderthe press especially adapted to the pressing of plastic materials asarticial resins, insulating materials or the like.

The invention is clearly illustrated in the accompanying drawings, inwhich:-

Fig. 1 shows diagrammatically the motions in connection with thearrangement of the cranks.

Fig. 2 is a side View of the press,

Fig, 2a is a front view of the press,

Fig. 3 is a longitudinal section of the slip coupling, and

Fig. 4 is a cross section of the slip coupling or clutch.

For this purpose the employment of. double cranks provides aparticularlyv great advantage as is illustrated diagrammatically inFigure 1 of the accompanying drawing.

In this gure a represents the pressing crank, b the auxiliary crank, cthe pull bars connecting the two cranks and d the connecting rod leadingto the press plunger e.

According to the invention the two cranks are so arranged with respectto one another that at the end of the pressure applying stroke of thepressing crank a, the pull bars c pass approximately through the centreof rotation of the auxiliary crank b. From this it will be seen at oncethat to a great motion of the crank b there corresponds at this place avery short motion of the press plunger e. Thus considerable power isapplied just when the press plunger is in its bottom position andartificial resins can consequently be pressed particularly effectively.During the upward motion of the plunger the latter lifts correspondinglyslowly from the pressing mould, so that the pressed article can belifted undamaged out of the mould, (Fig. 1 broken lines). 5

According to the invention the press is furthermore so constructed thatduring the continuation of its stroke the pressing crank moves veryrapidly, so that the idle running period of the press is lvery short.For this purpose according to the 10 invention the two cranks are soarranged with respect to one another that at the end of the lifting offstroke of the pressing crank a the pull bars e pass approximatelythrough the centre of rotation of the crank a, as is shown in Fig, 1 byfull lines. 15

The motions occurring between these two positions are indicated in Fig.1 by ve intermediate positions. It will be seen that with constantdistance of travel of the auxiliary crank b, the distances of travel ofthe press plunger are at rst 20 very great but become very small in thelower pressing position. By simply measuring the distances it will beseen that to the first sixth=16.6% of the motion of the auxiliary crankb there corresponds a motion of 32.3% of the stroke of the 25 pressplunger, while to the last sixth of the motion of the auxiliary crankthere corresponds only 1.6% of the stroke of. the press plunger. Thus avery rapid idle stroke and a very slow highly effective pressing strokeare obtained. 30

In designing this construction it has been found to be of advantage togive the auxiliary crank b the same radius as the pressing crank a. Fromthe constructional point of view this results in the simplestconditions, more particularlyif the pull 35 bars c be made longer thanthe distance between the centre of rotation of the two cranks.

Fig. 2 shows a constructional form of such an arrangement of a press. Onthe top of the press y frame m an electric motor n is mounted, which 40drives through gearing o of the auxiliary crank b, consisting of aplurality of. toothed wheels. For smaller types of presses it is notnecessary to provide an electric motor, in this case special means foroperation by hand will be suicient. Especi- 45 ally a handle or a leverarranged on a crank cheek may be used as is shown in Fig. 2 by dottedlines.

It is also possible to arrange a wheel provided with handles on thecrank shaft. Y

'I'he auxiliary crank is connected by the pull 50 bars c with thepressing crank a. On the crank pin of the pressing crank there is alsoarranged the connecting rod d which acts on the press plunger e. For therest the press corresponds to the usual oonstructional forms. 55

The constructional form of the press according to Fig. 2 shows anarrangement in which the pull bars c act directly on the crank pin ofthe pressing crank a. With this arrangement very favourably loading ofthe crank a is obtained, as it is by this means relieved of any torque.A plurality of connecting rods and a plurality of pull bars c may beprovided or the pull bars and connecting rods embrace one another in abifurcated manner. The advantage of the double crank drive may of coursealso be fully utilized if the drive of the pressing crank be derived inany other way from that of the auxiliary crank.

Furthermore a special slip coupling must be provided in order to preventoverloading of the press on the one hand in cases where too muchpressing material is placed under the press plunger and on the otherhand, when pressing plastic materials, to keep the pressing pressureconstant in the down position of the press plunger for the time duringwhich the plastic materials are flowing into all parts of the mould.

According to the invention this slip coupling is of the hydraulic type,the rotor of same being xed upon the one part of the shaft and thecasing or housing being attached to the other part of the shaft. Betweenthe suction and the pressure chamber of the coupling a bore has beenprovided in which a throttling or stopping means is arranged allowingthe liquid to flow through when the pressure has reached a certainamount. The interior of the casing is fully or partly filled with aliquid as for example oil, the liquid being sucked in by the rotor andbeing delivered back to the suction chamber by way of the bore. Whenusing oil the rotating parts are lubricated at the same time.

In ordinary Working the clutch chiefly acts as a rigid coupling in whichcase the liquid does not circulate at all. Only when the power to betransmitted has reached a certain amount the stopping means will beopened by the pressure produced and a relative movement of the rotortowards the casing will occur. In this way the pressure will be keptconstant without the plunger making any movement. The same result may beobtained when the motion of the press plunger is prevented by someobstacle as for example too much material in the press mould.

Instead of using a stopping means which opens only at a certain amountof pressure of the liquid a jet may be provided which always allows acertain circulation of liquid and which produces a certain throttlingeffect limiting the power to be transmitted.

For such a hydraulic coupling all known designs of pumps may be used,for example piston pumps, gear pumps, centrifugal pumps and so on. Theinvention relates to a special type of pumps having a rotoreccentrically arranged in the casing, this rotor having slots in whichblades are provided sliding on the inner part of the casing.

Figs. 4 and 3 show such a coupling in longitudinal section and crosssection. The casing or housing f is fixed upon the shaft g and isrotatably mounted on the shaft h, being made liquid-tight towards thisshaft by means of a packing bush. The rotor iis fixed upon the shaft h.It consists of a centre part in which slots are provided. In these slotsblades are slidably arranged of the same width as the centre part. Theblades Z slide with their outer part on the eccentric part p of thecasing and are pushed inward by the relative movement of the rotoragainst the casing as shown in Fig. 4.

When moving in this way the blades l suck liquid from the suctionchamber r and push it through the bore s. In this bore a spring loaded 5valve t is arranged through which, the valve being opened, the uid mayreturn to the suction chamber 1' by way of the bore u. The pressure ofthe liquid and correspondingly the power to be transmitted may bechanged by changing the tension of the spring w.

When the coupling rotates the blades are pushed outward by thecentrifugal force thereby tightening themselves suflciently against theeccentric part p. To assist the centrifugal force the slots lc areinter-connected by a groove D so that the fluid pushed inward by a bladewill push another blade outward.

I'he opening of the bore s must be situated near the end of the pressurechamber so that the liquid can flow out. In order to avoid too highpressure in those sections of the pressure chamber which are notcommunicated with the bore s openings :a are provided in the blades Z toallow a back ilow of the liquid. These openings a: are closed by theinward motion of the blades Z in such a way that the opening of a bladewill not be fully closed until the blade ahead in the turning directionhas given free the opening to the bore s.

The coupling will act as a slip coupling as described above when thedirection of rotation corresponds to the arrow y. When rotating in theother direction it will chiefly work as a rigid coupling on account ofthe liquid not being able to leave the pressure chamber.

If it is desired to have the coupling work as a sliding coupling in bothdirections of rotation another opening similar to the opening of thebore s may be provided near the narrowest part of the pumping chamber.This opening would have to lead to another stopping means correspondingto the valve t.

The hydraulic coupling has the special advantage that its outside formsa smooth cylinder which may be used as brake disc for brake shoes orbrake bands.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is:-

1. A press for artificial resins, insulating materials and other plasticmaterials comprising a frame, a press plunger, a crank drive adapted tomove said press plunger, an auxiliary crank, pull bars connecting saidauxiliary crank with saidv crank for the press plunger and means adaptedto drive said auxiliary crank by a source of power, the two cranks beingso arranged with respect to one another that at the end of thepressure-applying stroke of the pressing crank the pull bars passapproximately through the center of rotation of the auxiliary crank,while at the end of the lifting stroke of the pressing crank the pullbars pass approximately through the center of rotation of the pressingcrank.

2. A press as defined in claim l characterized by the feature that bothcranks have the same radius,

3. A press as dened in claim l characterized by the feature that thelength of the pull bars is different from the distance between thecentres of the cranks.

LA press for articial resins, insulating materials and other plasticmaterials comprising a 5 frame, a press plunger, a crank drive adaptedto move said press plunger, an auxiliary crank, pull bars, connectingsaid auxiliary crank with said crank for the press plunger and meansadapted to operate said auxiliary crank by hand, the two cranks being soarranged with respect to one another that at the end of thepressure-applying stroke of the pressing crank the pull bars passapproximately through the center of rotation of the auxiliary crank,while at the end of the lifting stroke of the pressing crank the pullbars pass approximately through the center of rotation of the pressingcrank.

5. A press for articial resins, insulating materials and other plasticmaterials comprising a frame, a press plunger, a crank drive adapted tomove said press plunger, an auxiliary crank, pull bars connecting saidauxiliary crank with said crank for the press plunger, means adapted todrive said auxiliary crank by a source of power, and a hydraulic slipcoupling arranged in alignment with the drive means for permitting aconstant slipping of long duration whereby the press will remaintemporarily under pressure while the drive continues to run.

6. A press as dened in claim 5 wherein the slip coupling includescommunicating suction and pressure chambers and throttling meansarranged between the suction and pressure chamber of the couplingadapted to allow a circulation of the liquid when the power to betransmitted reaches a certain amount.

7. A press for artificial resins, insulating materials and other plasticmaterials comprising a frame, a press plunger, a crank drive adapted tomove said press plunger, an auxiliary crank, one or more pull bars,links connecting said auxiliary crank with said crank for the pressplunger, means adapted to drive said auxiliary crank by an electricmotor, a hydraulic slip coupling which permits a constant slipping oflong duration arranged in the shaft line of the driving means andincluding communicating suction and pressure chambers, throttling meansarranged in the coupling between the suction and pressure chamber ofsame adapted to allow a circulation of the liquid when the power to betransmitted reaches a certain amount, means provided in the couplingadapted to allow a back iiow of liquid from sections in communicationwith the throttling means into the following section of the pressurechamber and a brake composed of brake shoes and a brake disc consistingof the outer part of the coupling which has the form of a cylinder.

8. A press for artificial resins, insulating materials and other plasticmaterials comprising a frame, a press plunger, a crank drive adapted tomove said press plunger, an auxiliary crank, pull bars connecting saidauxiliary crank with said crank for the press plunger, means adapted todrive said auxiliary crank by a source of power, and a slip couplingwhich permits a constant slipping of long duration arranged in alignmentwith the driving means and consisting of a hydraulic coupling includingcommunicating suc` tion and pressure chambers and throttling meansarranged between the suction and pressure chamber of the couplingadapted to allow a circulation of the liquid when the power to betransmitted reaches a certain amount, said hydraulic coupling alsoincluding a shaft, a rotor arranged concentrically on the shaft, acasing having the inner part arranged eccentrically to the shaft and therotor including blades which are moved inwardly when the rotor movesrelative to the casing.

9. A press as claimed in claim 8, wherein the rotor is provided withslots in which the blades slide and are connected by a groove allowingthe liquid to ow from one slot to the other.

10. A press as claimed in claim 8, wherein the communication between thesuction and pressure chambers consists of a bore, and the throttlingmeans includes a spring loaded valve and means for varying the load onthe valve.

11. A press as claimed in claim 8, wherein the blades are provided withan opening being so arranged on the surface thatV the openings enter theslot at the same time the blade ahead in the turning direction haspassed the communication point between the suction and pressure chamber.

12. A press as claimed in claim 8, wherein another opening, similar tothe opening of the bore, is provided in the vicinity of the narrowestpart of the pumping chamber leading to another stopping means whichcorresponds to the valve.

13. A press as claimed in claim 8, characterized by the feature thatinstead of a valve one or several jets are provided adapted to allow thecirculation of liquid with a resistance according to the power to betransmitted by the coupling.

KARL GTz.

